Solid lubricants are useful for conditions when conventional lubricants are inadequate, such as:
- Reciprocating motion. A typical application is a sliding or reciprocating motion that requires lubrication to minimize wear, as, for example, in gear and chain lubrication. ...
- Ceramics. Another application is for cases where chemically active lubricant additives have not been found for a particular surface, such as polymers and ceramics.
- High temperature. ...
- Extreme contact pressures. ...
What is a solid lubricant?
Solid Lubricant. A solid lubricant is a material used as powder or thin film which reduces friction and wear of contacting surfaces in relative motion and provides protection from damage.
What are liquid lubricants used for?
Liquid Lubricants Liquid lubricants are used extensively in applications that are high in terms of speed and load size. Liquid lubricants are the most dominant type of lubricant in the market. Liquid lubricants are comprised of base oil and some additives.
What are the applications of bonded coating of solid lubricants?
The popular applications of bonded coating of solid lubricants are cylindrical brushes, separator cage of rolling bearing, and electrical brushes. Solid lubricants can be further classified into four sub-types, namely polymer, metal-solid, carbon and graphite, and ceramic and cermet. Polymers are one of the largest groups of solid lubricants.
What applications are solid lubricants mostly used?
Solid lubricants are used primarily as extreme pressure (EP) or anti-wear type additives and are applied in one of three ways. The first and most popular application for solid lubricants, particularly molybdenum disulfide and graphite, is as an EP additive in grease formulations.
What are the advantage of solid lubricants?
In addition to providing reduced friction and wear, solid lubricants offer the advantage of permanent lubrication with no leakages. They generate low amounts of heat and offer low startup torque. Solid lubricants are ideal for use in the food industry, as they are NSF certified for food processing.
Where are solid lubricants preferred?
In places where the bearing has to be scaled against entry of dirty water, dust and grit. Machines where liquid lubricant cannot be maintained in position due to intermittent operations of machine parts such as shaft.
What is an example for solid lubricant?
The Most Common Type Of Solid Lubricants are: Graphite. Boron nitride. Talc. Calcium fluoride.
Which of the following are the disadvantage of solid lubricant?
Which of the following are the disadvantages of solid lubricants? Explanation: One of the disadvantages of the solid lubricants is poor heat dissipation. They have more ability to perform well at the high load too(under high pressures).
Is Vaseline a solid lubricant?
More often that not, it is sold in various forms in the market – Vaseline could be in the form of lotions, ointments or creams. It can also be used as a lubricant and it helps protect minor cuts and burns. On the other hand, petroleum jelly is made up of a semi-solid mixture of hydrocarbons.
Is grease a solid lubricant?
On the basis of its physical state, grease is classified as semi-solid lubricant.
Is graphite A solid lubricant?
Because the bonds between the sheets are weak, graphite shows lower shearing strength under friction force. Thus it can be used as a solid lubricant and has become one of traditional and primary solid lubrication materials.
What are the different types of lubricants?
There are three main types of lubricants: oil-based, water-based, and silicone-based.
Where are semi-solid lubricants used?
The most widely used semisolids lubricants are greases and Vaseline. In places where the bearing has to be scaled against entry of dirty water, dust and grit. Machines where liquid lubricant cannot be maintained in position due to intermittent operations of machine parts such as shaft.
Which is the most commonly used semi-solid lubricant?
The most widely utilized simple soap semi lubricant is calcium-based soap grease called multi-purpose grease. It offers temperature stability that can reach up to 65 degrees Celsius.
Where are liquid lubricants used?
These liquids are used to cool as well as to lubricate surfaces. Emulsions of oil in water are most widely used as cutting fluids. Lubricants are also used as cutting fluids in cutting, grinding, trading, and drilling of the metals.
Which of the following is a solid lubricant Mcq?
Explanation: Graphite is a solid lubricant.
What Are Solid Lubricants?
Solid lubricants have a lamellar structure preventing direct contact between the two surfaces coming in contact even at extreme conditions. Graphite and moly are commonly used lubricants. Solid lubricants are used as additives to oils and greases. They can also be added or alloyed into the surface when the component is been manufactured.
What is the purpose of lubricant?
Lubricants provide effective lubrication when the surface area (metal to metal or metal to plastic or plastic to plastic etc.) comes in contact and prevalent speed at that moment allows for effective formation of oil film and temperature range falls within the limit.
What is the most common type of lubricant?
The Most Common Type Of Solid Lubricants are: Moly, Graphite, and PTFE are most commonly used in the lubrication industry. Moly and graphite are extracted from mined ore whereas PTFE was created by Dupont chemical company and is manufactured by the company for many purposes.
What are the environmental factors that affect solid lubricants?
Environmental factors such as temperature, pressure, humidity, oxygen content, radiation, etc. Pertaining to the solid lubricants benefits and limitation, we can use above mentioned solid lubricants For eg: Moly has the highest load-carrying capacity with a low coefficient of friction.
What is solid lubricant?
A solid lubricant is a material used as powder or thin film which reduces friction and wear of contacting surfaces in relative motion and provides protection from damage. Solid lubricant friction is a special form of friction which occurs when using solid lubricants. It differs from friction models for liquid lubricants in view of the effects ...
What are the properties of solid lubricant?
Important material properties for solid lubricants include crystal structure, thermal and oxidation stability, volatility, chemical reactivity, melting point and hardness. Heat stability (in close relation to chemical stability) is required if thermal decomposition of the solid lubricant is to be avoided. Solid lubricants have a temperature range ...
What is a solid biodegradable lubricant?
12.13 Solid biodegradable lubricants. Solid lubricants are typically composed of a solid, a binder and additives such as corrosion inhibitors or solvents. Solid lubricants, which are used where it is important for the lubricant to stay in place, typically have a temperature range over which they are effective.
What is a grain type lubricant?
[328] have disclosed a grain-type lubricant useful for press forming or extruding of metal strips composed of dextrin, glutens and grain powders containing protein and carbohydrates from wheat flour, sweet corn powder, rice flour or soybean flour in 1–30% aqueous suspension.
What are the main binding agents used in lubricant?
The main types of binding agent used are organic resins, cellulose, and inorganic silicates and phosphates. Hydrocarbons and water are used as solvents. Emulsifiers are needed to disperse the product in water. Dry-film lubricants can be used in a variety of ways (dipping, spraying).
What is a solid metal forming lubricant?
Typical solid metal-forming lubricants are reactive soaps (salts of stearic, oleic and palmitic acid) in connection with a zinc phosphate coating. The main function of soaps (metal salts of fatty acids) in lubrication technology is in the preparation of greases (see Section 12.11 ).
What is lubricating grease?
The standard definition of a lubricating grease is ‘A solid to semi-fluid product of dispersion of a thickening agent in a liquid lubricant. Other ingredients imparting special properties may be included.’ The most common types of thickener are calcium and lithium metal soaps. Bentonite is used for high temperatures, above about 140°C. Esterified silica, vat dyestuffs and urea compounds are used for the most specialised applications.
What are the advantages of solid lubricant?
Ideally, it fills the entire bearing cavity without impeding the rolling elements and the physical nature of the polymer adds another layer of protection that grease alone could never offer.
How does solid lubrication work?
This material consists of countless micro-pores containing oil. The oil is released as the bearing operates, and when at rest, the pores reabsorb the oil.
What is the difference between greased and solid lubricant?
In contrast, the oil film between ball and race is more susceptible in greased bearings. The less oil within a bearing, the higher the risk of a catastrophic failure.
What happens when grease enters the bearing?
Importantly, when contamination enters the interior of a greased bearing, it will circulate with the grease, causing damage. Solid lubrication stops any contaminant that manages to work its way past the seal, keeping it away from the elements and races and preventing an inevitable failure.
How much of a premature bearing failure is caused by lubrication?
Remember, lubrication-related issues result in as much as 80% of premature bearing failures. By replacing greased bearings with those having solid lubrication, elimination of the human element from bearing maintenance is possible. This allows for:
What does "lenting additional strength to the seals" mean?
lending additional strength to the seals, decreasing the risk that they will deform or become compromised,
Is grease oil or grease?
and the introduction of contaminants through manual greasing. Grease is mostly oil. Thickeners and additives can modify the purpose and performance of the lubricant; for example, the need to resist high heat or extreme pressure. By reducing the lubrication within a bearing to just the oil, you eliminate issues related to greasing.
What is a solid lubricant?
Solid lubricants. A solid lubricant is a film of solid material composed of inorganic or organic compounds or of metal. There are three general kinds of inorganic compounds that serve as solid lubricants: 1. Layer-lattice solids: materials such as graphite and molybdenum disulfide, commonly called molysulfide, have a crystal lattice structure ...
What gases are used in lubricant?
The list of gases used in this manner is extensive and includes air, steam, industrial gases, and liquid-metal vapours. With so many types of materials capable of acting as lubricants under certain conditions, coverage of the properties of all of them is impractical.
What is the flash point of a lubricant?
The flash point, or the temperature at which a lubricant momentarily flashes in the pressure of a test flame, aids in evaluating fire-resistance properties. Like the pour-point factor, the flash point may in some instances become the major consideration in selecting the proper lubricant, especially in lubricating machinery handling highly flammable material.
Why do you lubricate sliding surfaces?
In equipment that handles gases of various kinds, it is often desirable to lubricate the sliding surfaces with gas in order to simplify the apparatus and reduce contamination to and from the lubricant. The list of gases used in this manner is extensive and includes air, steam, industrial gases, and liquid-metal vapours.
What is the penetration number of grease?
The penetration number, applied to grease, is a measure of the film characteristics of the grease. The test consists of dropping a standard cone into the sample of grease being tested. Gradations indicate the depth of penetration: the higher the number, the more fluid the grease.
What are some examples of soft solids?
2. Miscellaneous soft solids: a variety of inorganic solids such as white lead, lime, talc, bentonite, silver iodide, and lead monoxide are used as lubricants.
Which solids have a crystal lattice structure?
1. Layer-lattice solids: materials such as graphite and molybdenum disulfide, commonly called molysulfide, have a crystal lattice structure arranged in layers. Strong bonds between atoms within a layer and relatively weak bonds between atoms of different layers allow the lamina to slide on one another.
Why are solids used in lubricant?
Because of their solid consistency, solids may be used in applications where the lubricant must not migrate to other locations and cause contamination of other equipment, parts, or products. (7) Environmental.
What are the conditions for solid lubricant?
The most common conditions requiring use of solid lubricants are: (1) Extreme temperature and pressure conditions.
What is solid lubricant?
Solid lubricants can be utilized as free-flowing powders, as additives in some oils and greases, and as key ingredients in high-performance anti-friction coatings and anti-seize pastes. These special lubricant additives and powders fill in and level surface asperity valleys and peaks thanks to their adherence to the substrate ...
What is the load carrying capacity of lubricant?
Solid lubricants such as graphite and molybdenum disulfide normally demonstrate higher load-carrying capacity of up to 1,000 N/mm 2. They can play a role in preventing cold-welding and galling and are capable of providing lifetime lubrication under dirty and dusty conditions.
How much solids are in anti-seize?
Normally, anti-friction coatings will comprise around 30% solids blended with a resin binder and solvent carrier, while anti-seize pastes will consist of 40% to 60% solids in a base-oil carrier. Oils and greases may contain up to 10% of solids for lubrication during shock-load, start-up and shutdown conditions.
What are the advantages of white solids?
Other advantages of white solids include. Resistance to high temperatures. Good protection against fretting corrosion.
Which material has a weak bonding between layers?
Graphite with a layered lattice structure and weak bonding between layers delivers superior lubricity as long as the presence of moisture.
Is copper a good lubricant?
Copper is a soft metal with high plasticity and low shear strength, providing it good lubricating capabilities. Benefits of soft-metal solid lubricants include: However, they cannot be utilized with stainless steel at temperatures more than 1,000 °C due to the chance for galvanic corrosion.
Can you combine different types of lubricants?
It is possible to combine different types of solid lubricants in a coating or paste formulation to deliver certain synergistic results such as improved fretting-corrosion protection, optimal friction control and wear prevention, and increased load-carrying capacity. The advantages of using different combinations of solid lubricants are better than that of individual solid lubricants.
What is solid lubricant?
A solid lubricant is a solid material which is applied or inserted between two moving surfaces or bearing surfaces. This material will shear a lot more easily than the bearing or moving surfaces. The three main requirements for a material to be a solid lubricant are the ability to support the applied load without major distortion, a low coefficient of friction, and a low rate of wear. Solid lubricants are generally used when the conditions are extreme. Solid lubricants are used in a powder form, as lubricating grease, in suspensions, in metallic films, or in bonded lubricants. Anti-friction linings use solid lubricants.
What are lubricants?
Lubricants are substances which reduce friction and wear between two surfaces. It is applied at the interface of the two surfaces. Lubricants also help reduce the heat that is generated at the interface of the two surfaces that are in contact with each other and moving.
How does bonded coating affect lubricant?
These bonded coatings provide greater film thickness and increase the wear life of the lubricant and the surface on which the lubricant is applied. The popular applications of bonded coating of solid lubricants are cylindrical brushes, separator cage of rolling bearing, and electrical brushes.
What are the properties of lubricants?
Lubricants that are considered good or high-quality will normally possess the following properties: 1 High boiling point 2 Low freezing point 3 High viscosity index 4 Thermal stability 5 Hydraulic stability 6 Demulsibility 7 Prevention of corrosion 8 High resistance to oxidation
What type of lubricant is used in jet engines?
This type of lubricant was created to withstand harsh operating conditions. Jet engines use synthetic lubricants. These lubricants are expensive but they can withstand high levels of heat and stress. Some commonly used synthetic oils are esters, silicon, polyglycols, perfluoropolyalkylether, and perfluoropolyethers.
What is the best lubricant for space?
These solid lubricants contain lamellar solids and achieve low friction through a process known as film transfer. Molybdenum disulfide is the most commonly used metal-solid lubricant. Some of the advantages of a metal-solid lubricant like molybdenum disulfide are a high load carrying capacity, good high-temperature performance, and low friction. It is also stable in vacuum up to 1000 degrees Celsius. Hence, molybdenum disulfide also finds use in space applications. Its disadvantages are sub-optimal performance in the presence of moisture and high film thickness. A thicker film does not last as long because it is more prone to wear and tear.
What is the third type of mineral oil lubricant?
The third type of mineral oil lubricant is multigrade oil. It is made by adding polymers in mineral oils, thus enhancing the viscosity index of the lubricant. These lubricants have different grade levels whereby a specific grade of lubricant oil can offer optimal performance in low temperatures or in high temperatures.
What is the lubrication of solids?
The lubricity of many solids is attributable to a lamellar structure. The lamellae orient parallel to the surface in the direction of motion and slide easily over each other resulting in low friction and preventing contact between sliding components even under high loads. Large particles perform best on rough surfaces at low speed, finer particles on smoother surfaces and at higher speeds. These materials may be added in the form of dry powder to liquid lubricants to modify or enhance their properties.
What are the components of a solid lubricant?
Other components that are useful solid lubricants include boron nitride, polytetrafluorethylene (PTFE), talc, calcium fluoride, cerium fluoride, and tungsten disulfide.
What are the two main dry lubricants?
The two main dry lubricants are graphite and molybdenum disulfide. They offer lubrication at temperatures higher than liquid and oil-based lubricants operate. Dry lubricants are often used in applications such as locks or dry lubricated bearings.
What is dry lubricant?
Dry lubricants or solid lubricants are materials that, despite being in the solid phase, are able to reduce friction between two surfaces sliding against each other without the need for a liquid oil medium. The two main dry lubricants are graphite and molybdenum disulfide. They offer lubrication at temperatures higher than liquid ...
What is graphite used for?
Graphite. Used in air compressors, food industry, railway track joints, brass instrument valves, piano actions, open gear, ball bearings, machine-shop works, etc. It is also very common for lubricating locks, since a liquid lubricant allows particles to get stuck in the lock worsening the problem. It is often used to lubricate the internal moving parts of firearms in sandy environments.
Is PTFE a layered lubricant?
Contrary to the other solid lubricants discussed, PTFE does not have a layered structure. The macro molecules of PTFE slip easily along each other, similar to lamellar structures.
Is a layered crystal structure sufficient for lubrication?
However, a layered crystal structure alone is not necessarily sufficient for lubrication. In fact, there are some solids with non-lamellar structures that function well as dry lubricants in some applications. These include certain soft metals ( indium, lead, silver, tin ), polytetrafluroethylene, some solid oxides, rare-earth fluorides, and even diamond.
